US 10,502,045 B2 · Monitoring substances in a well annulus

Abstract

A system can include a current source electrically connected to casing in a wellbore, and a sensor including a monitoring electrode, a potential difference between the casing and the electrode resulting from current applied by the current source, and the potential difference indicating an impedance of a substance in an annulus external to the casing. A method can include positioning sensors spaced apart along a casing in a wellbore, each of the sensors including an electrode in electrical contact with a substance in an annulus, inducing current in the casing, and measuring a potential difference between the casing and the electrode at each sensor. Another system can include a current source, the current source being electrically connected to casing in a wellbore, and a sensor including a monitoring electrode and an electro-optical transducer that converts a potential difference between the casing and the electrode into strain in an optical waveguide.

Claims21

Dependent claims

A well monitoring system, comprising:

a current source electrically connected to casing in a wellbore to induce a current in the casing;
at least one sensor including at least one monitoring electrode;
an insulator positioned between the casing and the at least one monitoring electrode to partially electrically insulate the at least one monitoring electrode from the current in the casing;
and
wherein an electrical potential difference between the casing and the monitoring electrode results from current applied by the current source, and wherein the potential difference indicates an impedance due in part to at least one substance in an annulus formed between the casing and an earth formation.

2 more elements

Dependencies are inferred from the claim text.

Monitoring substances in a well annulus

Life of this patent

Monitoring substances in a well annulus

Life of this patent

Abstract

Claims21